Cessna P210N N450M

Summary

On 11 June 2001 at about 14:10 local time, a Cessna P210N registered N450M, operated by O & N Aircraft Modifications, INc., was involved in an accident near Honesdale, Pennsylvania, United States. 3 people were on board and 3 died. The aircraft was destroyed. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

11 June 2001 at 14:10

Classification

Accident

Location

Honesdale, Pennsylvania, United States

Coordinates

41.5697, -75.2506

Aircraft

Cessna P210N

Registration

N450M

Category

Airplane

Engines

1

Operator

O & N Aircraft Modifications, INc.

Operating rule

Part 91: General Aviation

Purpose of flight

Other Work Use

Phase of flight

Not recorded

Route

Factoryville → Unknown

Aircraft damage

Destroyed

Weather

VMC

Light

Day

NTSB number

NYC01FA141

3 people died.

An improperly manufactured torquemeter gearshaft assembly, which resulted in gearshaft assembly failure, an N2 overspeed, and a subsequent uncontained engine failure.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

The sales demonstration pilot was in the right seat and the prospective buyer was in the left seat. About 1 1/2 hours after takeoff, while in cruise flight at an altitude estimated by a witness to be between 3,000 feet and 3,500 feet, an explosion occurred in the engine compartment, and white smoke began emanating from the exhaust stacks. The airplane circled down to a forced landing in an area of rolling hills, farms, and pastures bordered by stone walls embedded with trees. As the airplane was nearing the ground, a witness saw it make a sharp left turn, then impact trees and a stone wall between two pastures. Area winds at the time of the accident were calm. The airplane was equipped with an overhauled Allison (Rolls Royce Corporation) 250-B17F2 engine which had been installed 9 months, and about 25 operating hours earlier. Teardown examination of the engine after the accident revealed a tri-burst of the third stage turbine wheel, due to an overspeed of N2 after a sudden loss of load on the power train. It also revealed a failure of the torquemeter gearshaft, from a crack which initiated in an area of intergranular separation, and subsequently progressed in high cycle fatigue. The intergranular separation resulted from "stress corrosion mechanisms during the AMS 2485 black oxide treatment [process]." The torquemeter gearshaft had been installed during the engine overhaul.

Quoted verbatim from the NTSB record.